The present invention relates to granular absorbents and more particularly to a granular absorbent which contains a neutralizing agent and is ideally suited for use as an animal litter.
A wide variety of granular absorbents have been proposed for use as animal litter. Typical granular absorbent material include cellulosic materials, such as, sawdust, wood chips, wood shavings, oat hulls, alfalfa (usually pressed or aggolmerated); or clay minerals, such as, kaolinites or montmorillonites. Unfortunately, such materials develop malodors rapidly when used as an animal litter.
Various attempts have been made to mask the odor expressed by granular animal litter, most typically involving the addition of a fragrance or deodorizer to the granular material. However, the fragrance or deodorizer is released continually and soon is exhausted. Another approach has been to provide a moisture sensitive release of fragrance. For example, U.S. Pat. No. 3,921,581 proposes a solid excipient having a water-sensitive disintegrant. The solid excipient is designed to disintigrate when the animal litter is moistened by urine. This animal litter, however, provides little or no oder masking for feces, and after a period of some use by the animal tends to develop moist clumps of disintegrated particles. A slightly more sophisticated approach is proposed in U.S. Pat. No. 4,407,231 which proposes an animal litter of absorbent particles which particles bear on their exterior surfaces frangible microcapsules which contain a fragrance or deodorizer. Known cellulosic materials, synthetic clays, and clay minerals are proposed. The fragrance or deodorizer is shown to be a perfume, flavor, fragrance, essence, oil, or deodorizer, preferably one which is fairly volatile, including citrus (orange or lemon) oil, oil of cloves, cinnamon oil, pine oil, or the like.
Heretofore, perlite, optionally admixed with clay, has been proposed for use in concrete, plaster, building forms, and the like. For example, U.S. Pat. Nos. 2,699,409 and 2,728,723 propose to use clay to agglomerate perlite fines, which agglomerate is suitable for use in concrete, plaster, building forms, etc. Alternatively, U.S. Pat. No. 2,778,744 proposes a granular odorant for use in bathrooms an other houshold rooms which odorant composition is composed of attapulgite, vermiculite, sawdust, or Fuller's earth, which material bears absorbed liquid odorant such as neutroleum alpha.
U.S. Pat. No. 2,884,380 proposes a molded thermal insulation composed of perlite, montmorillonite clay, an organic binder of polyvinyl acetate or emulsified asphalt, and silicone. U.S. Pat. No. 3,132,956 proposes an acoustical tile of perlite, optionally admixed with vermiculite, expanded clay, mineral wood, glass wood, artificially expanded glass, ceramic, or the like. The tile composition additionally contains a clay binder and the mixture is fired to cause a thin coating of clay to adhere to and bind the granular material into the acoustical tile form. U.S. Pat. No. 3,010,835 proposes a castable refractory mix of perlite, rock kyanite, calcined flint fire clay, and calcium aluminate cement. Canadian Pat. No. 835,822 proposes a method of making expanded perlite aggregates by firing at a temperature of 1600.degree.-2400.degree. F. a mixture of perlite, clay, and an alkali metal silicate flux. The aggregates are used to make lightweight structural panels. Canadian Pat. No. 835,823 proposes the same structural panel composition, except that the flux is omitted from the composition being fired.